All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Logic
Fibo's quickie (Posted on 2014-09-03) Difficulty: 1 of 5
You have 20 seconds (starting at the end of reading the puzzle)
to validate or to disprove the following formula of calculating
the area of a triangle:

S=1/3* ((2AB/C)+(2AC/B)+(2BC/A)).

where the sides A,B & C are represented by three different Fibonacci numbers.

See The Solution Submitted by Ady TZIDON    
Rating: 4.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Pie are squared | Comment 2 of 4 |
20 seconds of dimensional analysis are more than sufficient to disprove the above formula.

Areas must have units equal to length squared, but this formula has units equal to length, not length squared.

For instance, if A and B and C are in inches, the S is also in inches, so it cannot be an area.  It might be some sort of formula for perimeter, or semi-perimeter, or harmonic mean of the sides, or some other metric that has a dimension of length, but definitely not area.

It took longer to write this down than to it took to figure out.

And, by the way, that holds for any ABC, not just fibonacci numbers.  So I have proved (or disproved) more than requested.  Extra credit, Ady?

  Posted by Steve Herman on 2014-09-03 13:18:51
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (3)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2017 by Animus Pactum Consulting. All rights reserved. Privacy Information